An accurate and highly efficient method for finding antioxidant chemicals from Capsicum annuum L.

Abstract

Two-dimensional preparative high-performance liquid chromatography (HPLC) was used on the non-aqueous mobile phase in the separation of weakly polar compounds from Capsicum annuum L. The resulting silica column, coupled with an amide column, showed good orthogonality with the non-aqueous mobile phase, and two separate compounds were efficiently isolated in purity above 97%. The relative antioxidant activities of the purified compounds were assessed by a unique cellular antioxidant activity (CAA) model using an anti-oxidative response element (ARE) to regulate the expression level of the luciferase reporter gene, with tert-butyl hydroquinone (TBHQ) as positive control. A luciferase cellular antioxidant activity unit (LCAA) for the measurement of antioxidant capacity has been defined by the antioxidant capacity of 1.5 μg mL⁻¹ TBHQ, and the relative antioxidant capacities of two active compounds of interest, Fraction 5-4 and Fraction 5-5, were found to be 0.397 LCAA and 0.523 LCAA, respectively. The protocols described will be of considerable assistance in the development of functional foodstuffs.